The present invention relates generally to a dough feeding system for use in preparing dough products by lamination and lapping. More specifically, the invention relates to an apparatus and method for flexibly and precisely controlling the lapping of a variety of laminated dough webs, including, for example, extremely thin and delicate pre-formed dough webs, to avoid unwanted bunching, stretching, tearing, or other problems. The substantial flexibility and precision of the dough lapping system is achieved through the use of an independent controller for the reciprocating conveyor portion of the dough lapper.
In the production of numerous different types of dough products, e.g., danish, croissants, biscuits, etc., it is desirable to provide laminated dough comprising a plurality of layers of alternating fat (e.g., vegetable oil or shortening) and dough. The precise number of layers of laminated dough and the thickness and other characteristics of the dough that are desired in a given instance vary depending on the particular product being made. Ideal lapped dough characteristics also vary according to how the layered dough is to be treated in subsequent stages of the manufacturing process for a given dough product. Because of variability in the desired lapping parameters, and because the particular dough and lapping requirements for any product have to be integrated within the operation of the entire dough feeding system (i.e., the "dough feeding line") when those parameters change, it is extremely advantageous to have apparatus for dough lapping, which is adjustable to allow relatively easy variation in dough lapping, but an apparatus which is nonetheless capable of precise control.
Conventional dough lapping or laminating machines utilize various electro-mechanical apparatus to effectuate the lapping of the dough. In general, however, prior dough lapping machines comprise two basic, essentially motor-driven conveyors positioned at 90 degrees relative to one another. A top conveyor, typically referred to as the "infeed conveyor," has a portion which reciprocates back and forth to deposit layers of dough on a second, lower-positioned conveyor, commonly referred to as the "outfeed" or "takeaway conveyor."
The conventional infeed conveyor typically comprises several parts, including primarily an infeed belt, which is supported by underlying support apparatus, for moving the dough forward, and a reciprocating shuttle, which reciprocates relative to the infeed belt causing the dough to be lapped onto the takeaway conveyor. In conventional systems, a single infeed conveyor drive means (i.e., motor and gearing apparatus) effects motion of both the infeed belt and the reciprocating shuttle of the infeed conveyor. The reciprocating shuffle may include one or more separate shuttle belts, which are also driven by the same single drive means. Alternatively the reciprocating shuttle itself may simply interact with the infeed belt to advance and reciprocate it. Since both the infeed conveyor belt and the reciprocating shuttle mechanism (with or without additional belts) are controlled by the same single drive means, any desired adjustment to the operation of either the infeed conveyor or the shuttle mechanism affects the operation of both the infeed conveyor and the shuttle in a conventional dough lapper. (In contrast, it is typical for the takeaway conveyor to have a different and independently-controlled drive means from that used to drive the infeed conveyor and its various sub-elements.)
Generally, the structure, speed and placement of the drive means, including the motor, gears, sprockets, shafts and belts, and other electro-mechanical components for the infeed belt and reciprocating shuttle of the conventional infeed conveyor determine, among other things, the speed, direction, and length of travel of the infeed conveyor. Also, construction and placement of the infeed conveyor determine the smoothness of travel of the infeed conveyor and the infeed conveyor's position relative to the takeaway conveyor at all points during dough lapping. Accordingly, for a conventional infeed conveyor, construction of the infeed conveyor's single drive means is important for determining the manner in which the infeed conveyor will operate to lap the fat-treated dough.
Because the electro-mechanical components of the conveyors of a conventional lapper essentially determine or fix the lapping characteristics of the lapper, it is often difficult or impossible to modify the lapping characteristics without altering or changing fundamental structures or electro-mechanical components within conventional lapping apparatus. This is true even in dough lappers that use variable transmission systems, which are operatively interposed between the infeed conveyor drive means and the reciprocating shuttle, to add variability in controlling the reciprocating shuttle. Specifically, such devices allow the shuttle's linear speed to be varied with respect to the belt speed, but with somewhat limited precision. Moreover, such apparatus still does not allow the length of travel of the shuffle, i.e., "stroke length" to be adjusted, the stroke length being fixed by a linear gear. To affect such a change, physical components must be changed.
With a single conveyor drive means, certain operational characteristics cannot be fine tuned, so more preferable independent optimization of the operation of both the belt and shuttle is not fully possible in conventional dough lappers; that is, the certain operating features of the infeed conveyor are only subject to more or less gross control. For example, the manner in which the reciprocating shuttle slows as it approaches the end of travel in a given direction and speeds up as it begins travel in a given direction (i.e., "acceleration/deceleration profile") is not subject to precise control in a conventional dough lapper with a single drive means. Although compensating means and indirect control means can be added to offset the limitations of using a single drive means, the single drive means still ultimately limits flexibility.
U.S. Pat. Nos. 4,622,890, and 4,821,634, originally assigned to the assignee of the present invention (now assigned to the Moline Co. of Duluth, Minn.) and naming as inventor Peter Swanson, describe dough lappers generally of the kind sought to be improved by the present invention. The '890 patent describes a dough lapper having an infeed conveyor and a takeaway conveyor, the belts of which travel perpendicular to each other. The '634 patent describes a dough laminator in which the infeed conveyor and the takeaway conveyor belts operate in parallel, i.e., "in line." Both patents show or discuss distinct drive means for the reciprocating and takeaway conveyors, but show and discuss a single drive means for controlling the operation of the belt and the shuttle system of the reciprocating conveyor, as is typical in conventional dough lapping systems.
The apparatus of the Swanson patents do achieve some limited control of the shuttle of the reciprocating conveyor as a result of the use of an air cylinder to effect reciprocation of two additional shuttle system belts. However, while the air cylinder permits some additional control, the air cylinder (like in a system with an interposed variable transmission system) is also in driving connection with the same single drive means for the infeed conveyor.
Accordingly, the present invention is directed to providing greater control and flexibility of dough lapping by independently controlling the infeed conveyor belt and the reciprocating shuttle. The present invention permits the conveyor belt and shuttle mechanism to be adjusted relative to one another and relative to the takeaway conveyor, either as independent elements or in combined operation.
The present invention further provide for electronic control of a drive means to control the movement of the reciprocating shuttle mechanism, permitting precise control and flexibility of dough lapping characteristics. The controller should be capable of precisely affecting control of the speed of shuttle reciprocation relative to the speed of the infeed belt, the position at which the dough will begin to be deposited on the takeaway conveyor, and the width of the dough as it is lapped onto the takeaway conveyor.
The shuttle controller should be capable of determining the precise relative position of the conveyor's shuttle, and be capable of controlling the speed and acceleration of the shuttle, including when travel direction is reversed. The shuttle controller should also be capable of providing overtravel protection to override any inappropriately wide shuttle movement that may be brought about by, for example, improper data input by a human operator.